Pixels are available in 100 pixel 'blocks', with each block measuring 10x10 pixels. You will see the homepage is divided into 10,000 of these blocks.
The reason for selling them in these blocks is because anything smaller than 10x10 pixels would be too small to display anything meaningful.
Each 10x10 block costs only 1€, equating to a cost of 1 cent per pixel.
You can buy as many blocks of pixels as you like, as long as there are some available (see the live stats to the right). Click here to start advertising on the number 1 website for Costa Tropical, Spain.